In Ruby, you can use the sort method on an array to sort that array - but you cannot sort a hash. That's because of the techniques used within a hash to make it very fast to look up individual elements.

So what do you do if you want to sort something like this: ?

stuff = {"Steve" => "Kent", "Graham" => "Wiltshire",
  "Chris" => "Wiltshire", "Betty" => "Windsor",
  "Fred" => "Aberstwyth", "Harry" => "Potteries",
  "Sarah" => "Wiltshire"}

You get an array of the keys (using the keys method on the hash), and then you sort the list. To output the pairs from the hash in order, you step through the hash in the order given in the list and the job is done!

There's an example [here] in the examples directory - a piece of code I wrote as a demonstration during this week's Ruby Programming Training Course.

(written 2010-01-30)

 R107 - Collections (Arrays and Hashes) in Ruby
  [3435] Sorta sorting a hash, and what if an exception is NOT thrown - Ruby - (2011-09-12)
  [3257] All possible combinations from a list (Python) or array (Ruby) - (2011-04-23)
  [3255] Process every member of an array, and sort an array - Ruby - (2011-04-21)
  [3253] Is this number between? Does this list include? - Ruby - (2011-04-18)
  [2976] Creating, extending, traversing and combining Ruby arrays - (2010-09-30)
  [2621] Ruby collections and strings - some new examples - (2010-02-03)
  [2618] What are Ruby Symbols? - (2010-02-02)
  [2291] Collection objects (array and hash) in Ruby - (2009-07-16)
  [991] Adding a member to a Hash in Ruby - (2006-12-16)

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Cheat Sheet - what do you need for Ruby on Rails?
Scope of variables - important to Ruby on Rails
Search and replace in Ruby - Ruby Regular Expressions
Answers on Ruby on Rails
Sorting arrays and hashes in Ruby
Ruby on Rails - a sample application to teach you how
Tips for writing a test program (Ruby / Python / Java)
Ruby objects - a primer
East of Melksham - Building Work Starts
Ruby - is_a? v instance_of? - what is the difference?